(function init() {
    const docEle = document.documentElement;
    const resizeEvt = "orientationchange" in window ? "orientationchange" : "resize";
    const fontSize = function () {
        const clientWidth = docEle.clientWidth;
        if (!clientWidth) return;
        docEle.style.fontSize = 20 * (clientWidth / 375) + "px";
    }
    fontSize();
    window.addEventListener(resizeEvt, fontSize, false);
})();